Method of cooling the interior of a chamber



Dec. 16, 1969 J. MALczEwsKl 3,483,711

METHOD OF COOLING THE INTERIOR OF A CHAMBER to C 'L /:91 2

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METHOD 0F COLING THE INTERIOR 0F A CHAMBER Filed Jan. 29, 1968 2Sheets-Sheet 2 VAL VE CoA/WOL new c5 NVNT Jrmie malczewski BY W3,483,711 METHOD F CULING THF INTERIOR OF A CHAMBER Jrmie Malczewski,Boulogne, France, assignor to Societe Anonyme dite: Bronzavin,Courbevoie, France, a French society Filed Jan. 29, 1968, Ser. No.701,253 Claims priority, application France, Feb. 8, 1967,

im. ci. rzsd 17/06; Beate 1/00 US. Cl. 62--91 5 Claims ABSTRACT OF THEDlSCLOSURE This invention relates to a method of cooling the interior ofa chamber of which the walls are at a higher temperature than theatmosphere within the chamber7 and more particularly to cooling andconditioning the air within an airliner flying at supersonic speed.

Present air-conditioning devices for supersonic aircraft take off air athigh temperature from the jet engine compressors and distribute it inthe cabin at a temperature close to 0 C.

This cold air must not only renew the breathable air and maintain therequired cabin pressure, but must above all compensate for the heatcontribution from the walls of the cabin (which, for example at Mach 2,are at more than 120 C), so as to maintain the atmosphere within thecabin at about 24 C. It is this last function which determines thequantity of air flowing into the cabin and the temperature of this air.

Since, during supersonic flight there is no cold source (and at the mostvery limited heat sinks such as the fuel), such a conditioning devicerelies on a process based on a series of compressions and expansions ofair (the principle of the calorie pump). It is thus extremely complex,heavy and cumbersome.

A main object of the present invention therefore is to provide a methodwhereby the air introduced into a chamber under the conditions referredto above may be cooled, and especially when the chamber is the interiorof a supersonic aircraft, which method enables a considerable gain inweight of equipment to be achieved.

In general however the conditioning of a breathable atmosphere is notlimited to maintaining an ideal temperature; it is concerned also withproducing an acceptable humidity level.

ln transport aircraft cruising at an altitude greater than about 36,000feet, the humidity of the conditioned air is practically nil. It is thusdesirable to humidify the air within the cabin to improve the comfort ofthe passengers and it is also necessary to humidify the air of theflight deck so that the faculties of the crew members are not impaired.

Hitherto, for practical reasons, humidification has been limited to theflight decks of aircraft and for this purpose, a boiler was used heatedby an electric resistance consuming several kilowatt-hours. It will beobserved however that this process produces a considerable addition ofheat in the cabin which obviously has to be removed thus accentuatingthe cooling problem in a supersonic nited States Patent O 3,483,711Patented Dec. 16, 1969 ice aircraft. Moreover, the use of steam givesrise to numerous difficulties: The steam ducts have to be insulated,there is a risk of personnel being scalded at the output points of thesteam, and visible clouds of condensation vapour are very common.Numerous methods of avoiding these disadvantages have been tried, noneof which has proved wholly satisfactory.

One attempt to deal with this problem in a supersonic aircraft consistedin injecting a quantity of water into the air in the conditioning systembetween the air takeoff points in the engine compressors and the inletpoint for the air into the aircraft cabin. However, since the airentering the cabin is at 0 C., the water content of the conditioned airtends to freeze towards the cabin inlet so that some of it is depositedas frost in the pipes of the conditioning system and that entering thecabin appears as a frozen cloud or even snow. From the aspects ofmechanical eiciency of the conditioning system, and of passengercomfort, this method clearly leaves much to be desired.

A further object of the invention therefore is to provide a methodwhereby an acceptable humidity level can be maintained within the cabinof a supersonic aircraft without giving rise to the disadvantagesenumerated above.

According to the invention, a method of cooling the interior of achamber, the atmosphere within which is constantly renewed and of whichthe walls are at a higher temperature than the atmosphere within thechamber, comprises injecting into the chamber a controlled amount of afinely atomised liquid spray at a point where the temperature of theatmosphere is sufficiently high to evaporate the liquid, and evacuatingthe vapour so formed before it reverts to the liquid phase.

Experience has shown that the vapourisation of finely divided dropletsof water diffused in the air of the chamber absorbs a large quantity ofheat upon evaporations and it is essential that the vapour be evacuatedfrom the chamber whilst it contains this heat. Thus in the method of theinvention, the vapour is essentially evacuated from the chamber beforereverting to the liquid phase. The quantity of liquid injected may becontrolled automatically in dependence upon the temperature of thechamber interior to maintain the latter at a constant temperature. Thisis particularly important where the chamber is the interior of asupersonic aircraft since large quantities of heat are continually beingproduced during supersonic flight due to air-friction on the outer skinof the aircraft. lt is important to observe that when the method of theinvention is employed, the same means are used both to cool and humidifythe atmosphere within the aircraft and a very considerable saving inWeight for the conditioning system is obtained.

The invention will now be described in greater detail by way of examplewith reference to the accompanying drawings in which FiG. l is aschematic sectional view of a device for simulating the conditionsprevailing in the cabin of a supersonic aircraft flying at supersonicspeed, in which device the method of the invention was carried out andmeasurements made,

FIG. 2 is a graph illustrating the variation of the quantity of dry airto be introduced as a function of its temperature, in order to maintainin the simulator a substantially constant temperature, whilst anatomised water spray maintains a 40% relative humidity in the chamber,

FIG. 3 is a sectional view of the cabin of a supersonic aircraft showingone manner in which a series of atomisers may be arranged to carry outthe method of the invention.

To demonstrate the advantageous results obtainable by employing theprinciple of the present invention, there will now be described someexperiments in air conditioning which are carried out using the verysimple simulator device illustrated in FIG. l. It will be recalled firstof all that in an aircraft iiying at Mach 2 to 2.5 there is provided foreach passenger:

a cabin volume of 1 rn,

a ow of conditioning air q of 0.010 kg./s.,

an air temperature to at the air inlet of the cabin of C.,

an air temperature t2 at the air outlet of the cabin at In order toreproduce these normal conditions, the simulated cabin comprises anopen-topped metal tank 1 of which the internal dimensions are 1m X lm X1m. This tank is housed in a completely thermally insulated casing 2 sothat external conditions have no iniiuence within the tank. Chocks (notshown) maintain the tank uniformly spaced from all the walls of thecasing which has a central upper opening 3 to admit conditioning air anda lower central outlet 4 for evacuation of this air. The air circulatesin the direction shown by the arrows, from the opening 3 towards thetank 1 through which it passes and from which it escapes from the opentop of the tank and through the space provided between the tank and thecasing after which it is evacuated through the opening 4.

A generator of cold and dry air is connected to the opening 3, adischarge meter enabling the quantity of air q admitted to the simulatedcabin to be controlled. Moreover, an electrical resistance 5 is woundaround the tank to simulate the addition of heat to the walls of thecabin of a supersonic aircraft. It is connected to an autotransformer,an ammeter and a voltmeter enabling the supply of electric current to-be accurately controlled. Thermocouples are conveniently disposed tomeasure the temperature of the air tn at the inlet, t1 in the tank andt2 at the outlet. In this form, the simulating device enables normalconditions prevailing in the cabin of a supersonic aircraft flying atsupersonic speed to be reproduced. Thus by regulating the quantity ofair q at a level of 0.010 kg./s. and the inlet temperature to to 0 C.and by regulating the heat supply so that the temperature at the outlett2 is 40 C. (the electrical power being 400 w.), the mean temperature t1in the tank 1 can be maintained at 24 C.

T'he purpose of these experiments is to determine the in uence of anatomised water spray in the tank 1 on the air conditioning. To thiseffect, an atomising generator 6 (of the centrifugal type driven by anelectric motor) is disposed underneath the air inlet 3. In all theexperiments, the heating is maintained at a constant level, since theexperiment simulates a predetermined supersonic flight havingpractically invariable parameters.

In a first experiment, no change is made to the entry temperature of theair or to the quantiy of air employed, which remain respectively at 0 C.and 0.010 kg./s. An atomised spray is injected at a rate of 0.0001kg./s. which engenders and maintains in the tank 1 a mean humidity ofabout 40%. It is observed that in the mean temperature in the tank 1 andin the exit temperature t2 there is a drop of about 20 C. It may thus beconcluded that in these conditions the diffusion of atomised waterenables the temperature to be lowered and a satisfactory humidity levelto be created.

In a second experiment the flow of dry air entering the chamber is keptat q:0.0l0 kg./s. and the atomised spray discharge rate is held at1:00001 kg./s. so that the humidity remains at 40%, but by regulatingthe entry temperature to, it is desired to obtain a mean temperature inthe tank 1 and an exit temperature substantially equal to the normaltemperatures i.e. 151:24" C. and 12:40 C. It was found that the entrytemperature Z0 must be 22 C. It can thus be concluded that in theseconditions, the diffusion of the atomised spray enables air to beadmitted at a higher temperature whilst maintaining a relativelysatisfactory ambiant temperature and humidity.

In a third experiment, the inlet temperature t0:0 C., is maintainedconstant but the quantity of dry air q entering the chamber and thequantity of atomised spray injected thereinto are adjusted so that thehumidity remains substantially at 40%. It is desired to maintain thetemperatures in the tank 1 and at the outlet in the region of the normaltemperatures, namely t1\:24 C. and t2:40 C. It was observed that thequantity of air q must be regulated to 0.0064 kg./s. It can thus beconcluded that in these conditions, the diiusion of the atomised sprayenables the quantity of air circulating to be reduced whilst maintaininga relatively satisfactory ambiant temperature and humidity.

Other intermediate experiments were carried out, by modifying at thesame time the entry temperature to and the quantity of dry air q so asto obtain a mean temperature 11:24" C. in the tank, an outlettemperature t2:40 C. and a humidity of 40%. The surve 7 of the graph ofFIG. 2 illustrates the results obtained: the quantities q in kg./s. areshown on the abscissae and the temperatures t0 in C. on the ordinates.

It is clear from these experiments that the diffusion of an atomisedliquid spray in the chamber provides a very simple and economical methodof conditioning the air within the chamber which ena-bles simultaneouslyheat to be evacuated from the chamber and a desired humidity to bemaintained. In the particular case of conditioning the air within thecabin of a supersonic aircraft, the advantages are even more pronounced.These will be expressed in approximate iigures hereunder.

In the case of an aircraft having l0() seats flying for l hours at Mach2 to 2.5, the ow rate of conditioning air is 1 kg./s. This air entersthe cabin at 0 C. and is evacuated in the baggage compartment at 40 C.

If the conditioning is carried out by dilfusion of an atomised sprayinto the cabin on the basis of the second experiment (namely the sameair flow q but higher entry temperature to), the additional weight is asfollows:

Weight of water consumed 2 3, 600X0.000l:72 kg.

Since this weight will be zero at the end of the ight, the

Total Diminution of heat losses in the cold piping.

However, if the conditioning is carried out on the basis of the thirdexperiment (namely same entry temperature to and diminished waterinjection q) the weight required is as follows:

Weight of water consumed :100 0.00064 2X3, 600:46 kg.

Since this weight will be zero at the end of the flight the Averageweight will be 4%-1-2 25 Weight of water reservoir i Weight of 4atomisers i5 Total aa-...my a-l-.m- 36 The gain in weight with respectto a classic conditioning system is:

Reduction of 36% of air flow rate in the conditioning system andtherefore a gain in weight Kg. of at least on 600 kg. 90 Elimination ofthe humidier on the flight deck 15 Total 105 Diminution of 36% in theseries of exchangers. Diminution of 36% in the take oif of air from theengines.

In practice, the optimum solution which should be chosen is situated onthe curve 7 in the vicinity of the abscissa axis.

The water can be atomised and sprayed by any convenient atomising devicebut for preference a device is used employing rotating discs which arewet by a continually renewed layer of water in which atomisation of thelayer takes .place centrifugally.

FIG. 3 shows diagrammatically in cross section the fuselage of asupersonic airliner incorporating a system for carrying out the methodof the present invention, and comprising an outer skin 1 within which isdened by an inner wall 2 a cabin 3 in which the seating positions of thepassengers are represented. The interior of the fuselage includes abaggage compartment 4.

Dry breathable air is supplied to the interior of the cabin from aconventional air conditioning device (not shown), the air entering thecabin through the ducts shown at 5. Two entry points for atomised liquidare shown at 6. In the present embodiment it may be considered that thedry air enters the cabin at 0 C., and for this reason the liquid isinjected into the air some distance from the entry point of the latterinto the cabin where it is at a temperature greater than 0 C., therebyavoiding condensation and freezing phenomena. A possible circulationpath of air and liquid in the fuselage is shown, and it will be seenthat the heated atmosphere is removed from the cabin at the opening 7and transferred, as shown by the arrows, via the ducting 8 between thefuselage 1 and cabin wall 2 into the baggage hold 4 whence it isevacuated through the opening 9.

The fuselage walls may be in the region of 150 C. during supersonicflight of the aircraft, and the method of the invention enables theinterior cabin temperature to be maintained at approximately 24 C.whilst at the same time enabling a satisfactory humidity level to bemaintained without the addition of heavy auxiliary apparatus.

The dry air entering the cabin may be at a temperature higher than 0 C.,for example 15 C., before entering the cabin, and in this case theliquid injection points 6 may be in the immediate vicinity of the airinlets 5 since there is no question of condensation or freezingoccurring upon mixing the liquid and air.

It will be appreciated that liquid injection points may be distributedthroughout the cabin and ight deck of the supersonic aircraft insuicient quantities and in such locations as to maintain a substantiallyconstant predetermined cabin temperature and humidity. The liquid mostcommonly used is water, although various substances such as perfumes ordisinfectants for example may be mixed with the basic liquid.

The delivery of water to the entry points 6 can be readily controlled inaccordance with the cabin temperature by providing one or morethermocouples 11 in the cabin and by connecting the thermocouple to asuitable control device 12 which is connected by line 13 to control theoperation of a valve 14 regulating the rate of delivery of liquid toconduits 15 feeding entry points 6.

What is claimed is:

1. A method of cooling the interior of an airborne vehicle whoseexternal Walls are at a temperature above that to be maintained in theinterior, comprising the steps of: continuously introducing into theinterior of the vehicle air at a temperature below that to be maintainedin the interior; injecting a nely atomized evaporatable liquid into theinterior at a point where the temperature is sufciently high tocompletely evaporate the liquid; and continuously evacuating aircarrying the resulting vapor before the vapor can revert to its liquidphase.

2. A method according to claim 1 wherein the quantity of liquid injectedis controlled automatically in dependance upon the temperature of thevehicle interior.

3. The method of claim 2 wherein vehicle is a supersonic aircraft, theliquid is water and is injected at such points and in suicientquantities to ensure maintenance of a substantially constantpre-determined temperature and humidity.

4. The method of claim 3 wherein the air is introduced into the interiorat a temperature of about 0 C. and the liquid is injected at a pointremote from the atmosphere entry point.

5. The method of claim 3 wherein the air is introduced into the interiorat a temperature above 0 C. and the liquid is injected at a point closeto the atmosphere entry point.

References Cited UNITED STATES PATENTS 1,749,763 3/193() Fleisher 98-302,199,485 5/1940' De VOut 62-121 X 3,110,613 1/1964 Evelyn et al 244-117X 3,363,531 1/1968 Kohlmeyer et al 98-30 WILLIAM E. WAYNER, PrimaryExaminer U.S. Cl. X.R.

gjgo NITED STATES PATENT OFFICE CERTIFICATE 0F CORRECTION Patent No.3,483,711 DatedDecember 16th, 1969 Inventor (s) T rmie Malc z ewski Itis certified that error appears in the above-identified patent and thatsaid Letters Patent are hereby corrected as shown below:

Column l, line 5, change "Bronzavin" to -Bronzavia. Column 4, line 66,change "0.00064" to 0.000064.

SIGNED AND SEALED MAY 1 21970 QSEAL) Attest:

WILLIAM E. 'SOI-TUNER, JR. Edward M- Fletcher, In Commissioner ofPatents Attesting Officer

